Antimicrobial and Antioxidant Activities of Secondary Metabolites of an Endophytic fungus of Azadirachta indica

Abstract

Background: Recent upsurge in the mortality rate and long hospital stays as a result of antimicrobial resistance caused by multi-drug resistant bacteria is a huge burden to public health sector. Intensive search for more effective and newer agents to deal with these problems. Endophytes are a novel source of potentially useful medicinal compounds. Aim: The study aimed at evaluating the antimicrobial and antioxidant activities of an endophytic fungus isolated from Azadirachta indica against multi drug resistant bacteria species. Method: Endophytic fungus was isolated from fresh leaves of Azadirachta indica. The fungus was fermented in rice medium, and the secondary metabolites were extracted. The antimicrobial activity of the extract against laboratory strains of Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia and Bacillus subtilis, Candida albicans, Aspergillus niger) was determined. The fungal extract was also evaluated for antioxidant activity using the DPPH assay method. Using GC-FID analysis, some constituents of the fungal extracted were identified. Result: At 1 and 0.5 mg/mL, the fungal extract demonstrated antibacterial activity against Klebsiella pneumoniae but no activity against the other test microbes. However, the fungal extract of A. indica showed excellent antioxidant activity due to possession of bioactive secondary metabolites. Conclusion: The result of GC-FID showed the presence of Rutin, Lunamarin, Anthocyanin, Catechin, Naringenin, Flavan 3 ol, Sapogernin, Tannin, Spartein, Naringin, Flavonones, Steroids, Kaemferol, Cyanogenic glycoside, Phytate, Epicatechin, Reseveratol, Cardic glycoside and Epihedrine at different concentrations. This study reveals the dynamic potentials of the endophytic fungus of A. indica as the bedrock of naturally occurring bioactive agent. 
 Keywords: Azadirachta indica, endophytes, GC-FID, secondary metabolites, medicinal plants, phytochemicals.